There are many problems related to the disposal of bulky waste materials, and attempts have been made in the art to reduce the number of sequential passes required to shred or granulate waste materials to the desired size. For example, U.S. Pat. No. 5,562,255 (Witko '255) teaches a tire-shearing machine that shreds and granulates in a single pass, using two different pairs of cutters. The tire shredding machine taught by Witko '255 is comprised of pairs of rollers which first flatten the tire. The rollers are positioned above a rotating primary shear so that the primary shear segments the flattened tire along a longitudinal axis into a plurality of longitudinal strips. The strips are then fed into an independent rotating secondary shear, placed below the primary shear. Pieces from the primary shear are held between shear members until a scraper forces the pieces into the secondary shear. The scraper also positions the pieces so that they are cut properly by the secondary shear. The secondary shear cuts along an axis perpendicular to the longitudinal axis cutting each of the longitudinal strips into a plurality of small chunks. The speed of each shear is controlled independently of the other allowing the size of the chunks produced to be varied.
The tire-shearing machine taught by Witko '255 is a somewhat complex design in that material to be shredded or granulated must pass though a first rotating shear, drop accurately, and then pass through a second rotating shear. The timing and coordination of both rotational processes is critical, and the settings must be adjusted to provide segmented pieces of a desired size. The separately rotating shears are subject to jamming, and the tire-shearing machine taught by Witko '255 requires four drive (motor) components to separately drive each of the four shafts.
A problem known with the tire-shearing machine taught by Witko '255 is that the material to be sheared or granulated must pass in a relatively uncontrolled manner from a first tier of rotating shears to a second tier of rotating shears. Additionally, the speed of the descent from the top tier of rotating shears to the bottom tier of rotating shears is uncontrolled, resulting in variable sizes of sheared and granulated materials.
It is desirable to have a single pass shredder-granulator that eliminates the need for two sets of rotating shears.
It is further desirable to have a single pass shredder-granulator that produces consistently sized shredded and/or granulated pieces.
It is further desirable to eliminate any distance between two sets of rotating shears where the speed or angle of descent of the material to be sheared or granulated cannot be physically controlled.
It is further desirable to have an efficiently designed shredder-granulator that minimizes the number of moving and assembled parts, and which can perform shredding and granulating processes in a single pass.